Conventionally, cycloolefin-based polymers have been broadly utilized as forming materials or the like, since they exhibit excellent transparency, low hygroscopicity, excellent heat resistance, excellent insulation property, excellent chemical resistance, excellent impact resistance and the like. However, the above properties inherent in the cycloolefin-based polymer were sometimes impaired when a resin composition was prepared by adding a flame retardant in order to improve the flame retardance of the resin composition including the cycloolefin-based polymer.
As a resin composition capable of solving this problem, Patent Literature 1 describes a flame-retardant resin composition including a particular norbornene-based polymer and a halogen-containing flame retardant. This resin composition is considered to maintain mechanical strength and chemical resistance inherent in the norbornene-based polymer and have excellent flame retardance.
However, as the resin composition described in Patent Literature 1, when a resin composition including a norbornene-based polymer and a halogen-containing flame retardant was used as a forming material for a circuit board such as a printed wiring board, the dielectric constant and the dielectric loss tangent were increased in some cases, and thus the resin composition was not necessarily suitable as a forming material for a high-frequency circuit board.
Thus, a flame-retardant resin composition having excellent flame retardance, and low dielectric constant and low dielectric loss tangent, has been required.